This invention relates generally to an electronic timepiece including a piezoelectric type alarm buzzer, and more particularly to an electronic timepiece wherein the piezoelectric element is mounted on the timepiece back which functions as the buzzer diaphragm.
Conventional electronic timepieces, such as wristwatches including an alarm device with a vibrating caseback include constructions wherein a piezoelectric element is mounted to the caseback. These timepieces utilize the piezoelectric effect to generate sounds as is well known in the prior art. Generally speaking, the piezoelectric element is formed with electrodes on the upper and lower sides and is adhered to the caseback by means of a conductive adhesive. Conducting spring members are generally provided to connect the piezoelectric element to the alarm circuit of the timepiece movement and maintain a space between the piezoelectric element and the movement and battery. Generally, a sufficiently large gap is maintained between the battery and the piezoelectric element in order to prevent short-circuiting due to contact when the timepiece is subjected to pressure or impact.
An example of this type of construction is illustrated in U.S. Pat. No. 3,879,931. Alternatively, the patentees place the battery adjacent to the vibrating caseback which results in a diaphragm of reduced size, and consequently, reduced sound level. Accordingly, as a result of this, such prior art constructions are not totally satisfactory in that the thickness of the timepiece is increased significantly or the sound level is reduced. Accordingly, it is desirable to provide a timepiece including a piezoelectric alarm buzzer of reduced thickness which will not be subject to shortcircuiting between the battery and the piezoelectric element and will not affect adversely the sound level.